This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Our goal is to investigate the chromatin structure during activation of transcription and to examine mRNP morphology at the transcription site and in the nucleoplasm using tetracysteine-biarsenical probes, correlated live imaging, and electron microscope tomography. The application and adaptation of these techniques to our system will be developed in collaboration with NCMIR/UCSD.